Plunger pump cylinder for use in treating highly corrosive fluid

ABSTRACT

A plunger pump cylinder for use in treating highly corrosive fluid. The pump is composed of two parts, a cylinder body and a valve seat body. The valve seat body has a central longitudinal bore formed therein, and it is fitted within a bore formed in the cylinder body. At the respective ends of the bore in the valve seat body are an inlet valve and a delivery valve.

United States Patent [1 1 Iguchi et al. [451 Jan. 9, 1973 s41 PLUNGERPUMP CYLINDER FOR USE 3,106,169 10/1963 Prosser etai ..4l7/569 INTREATING HIGHLY CORROSIVE 3,508,849 4/1970 Weber ..417/569 FLUID3,260,217 7/1966 Thresher.. .....417/567 3,114,326 12/1963 Yaindl..4l7/567 [75] Inventors: Jintaro lguchi; Hiroyukl Tokushlge, 3,180,2774/1965 Thresher ..4l7/567 both of Hiroshima, Japan 3,431,865 3/1969 Cooket al. ..417/571 [73] Assignee: Japan Steel Works Ltd., Tokyo, FOREIGNPATENTS OR APPLICATIONS 391,034 3/1962 Great Britain ..4l7/567 [22[Filed: Oct. 22, 1970 993,887 6/1965 Great Britain ..4l7/569 [2]] Appl'83371 Primary ExaminerWilliam L. Freeh I 30] Foreign ApplicationPriority Data Assistant Examiner.lohn J. Vrablik Feb. 24, 1968 Japan..43/l3668 f Related U.S. Application Data [57] ABSTRACT [63]Continuation-impart of Ser. No. 796,454, Feb. A plunger pump cylinderfor use in treating highly 1969, abandonedcorrosive fluid. The pump iscomposed of two parts, a 7 cylinder body and a valve seat body. Thevalve seat U.S-

has a entral longitudinal bore fgfmed therein [51] Int. Cl. ..F04b21/02, F041) 39/10 and it is fitted within a bore formed in the cylinderField of Search 569-571 body. At the respective ends of the bore in thevalve seat body are an inlet valve and a delivery valve. [56] ReferencesCited 1 Claim, 2 Drawing Figures UNITED STATES PATENTS 1,628,096 5/1927Worth ..4l7/567 PATENTEDJAN 9 I973 IINTARD IGUCHI H IROYUKI TOKLISHlC-EINVENTORS BY ATTORNEE PLUNGER PUMP CYLINDER FOR USE IN TREATING HIGHLYCORROSIVE FLUID This is a continuation-in-part application of Ser. No.796,454 filed Feb. 4, 1969 now abandoned.

BACKGROUND OF THE INVENTION This invention relates to a plunger pumpcylinder, and more particularly to a plunger pump cylinder which is usedfor handling highly corrosive fluid.

With the progress of the chemical industries and the development of newprocesses, the conditions under which pumps used in these industriesmust operate have become more and more severe.

The corrosiveness, pressure and temperature of fluids being handled havebecome more severe. This is especially true for plunger pumps whichhandle such fluids. These pumps are subject to a repetitive load due tosuction and delivery pressures, and, accordingly, when they handle ahighly corrosive fluid, cracks often occur in the cylinder within arelatively short period of time due to corrosive fatigue caused by theconcentration of stress therein. Such cracks grow, and the pumpeventually becomes unusable. This is a defect inherent in conventionalplunger pumps used for highly corrosive fluids.

SUMMARY OF THE INVENTION It is an object of the present invention toprovide an improved pump for handling highly corrosive fluids which doesnot have these deficiencies.

In order to prevent a plunger pump cylinder for handling corrosive fluidfrom developing cracks due to corrosive fatigue, the present inventionprovides a new cylinder construction in which the intersecting portionsof various bores in the cylinder are, when in use, subject only tosuction pressure and are not subject to delivery pressure.

According to the present invention, this is achieved by a constructionof the cylinder in which the cylinder body having a suction port in oneof its sides has a separate valve seat body having a centrallongitudinal bore fitted within a central longitudinal bore formed inthe cylinder body. Said bore in the valve seat body is placed in fluidcommunication with the suction port through an annular groove formed inthe central longitudinal bore of the cylinder body and fluid passagesformed in the valve seat body. By this means the inlet valve and thedelivery valve are arranged on a line so that they lie at opposite endsof the longitudinal bore of the valve seat body.

Thus, in the pump cylinder according to the present invention, only alow load due to suction pressure is applied to the portions formed bythe intersection of bores in the cylinder, so that no fatigue due to arepetitive load is caused at these portions.

Therefore, according to the present invention, even when the plungerpump handles highly corrosive fluid, the cylinder is prevented fromdeveloping cracks due to corrosive fatigue, and hence the life of thepump cylinder can be greatly increased.

Other object and advantages of this invention will become apparent fromthe following description taken with the accompanying drawings, whereinare set forth, by way of illustration and example, a conventionalplunger pump cylinder and an embodiment of this invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectionalview of a conventional plunger pump cylinder; and

FIG. 2 is a longitudinal sectional view of an embodiment of the pump ofthe present invention.

In a conventional plunger pump, as shown in FIG. I, a suction port I anda delivery port 2 are arranged side by side on one side of a cylinder 3,and on the other side is provided a plunger 4 slidable in a stuffing box5. In suction port 1 there is a suction valve 6 which is urged againstits seat by a coil spring 7 disposed on a spring support 8. In deliveryport 2 there is a delivery valve 9 which is urged against its seat by acoil spring 10. In the inside of cylinder 3, there are longitudinalbores 11 and 12 and a transverse bore 13 for placing suction valve 6 incommunication with delivery valve 9. It will be seen that, in theportions of the inner surfaces of cylinder 3 contacted by fluid, asshown in FIG. 1, there are sharp edge portions 14 at the intersectionsbetween longitudinal bores 11 and 12 and transverse bore 13, which, whenthe inner surface of cylinder 3 is subject to a repetitive load due tothe alternating suction pressure and delivery pressure, is subjected toa repeated concentrated stress. In a corrosive atmosphere, the fatiguelimit of the material of the cylinder is reduced, and the more severethe corrosive conditions, the greater the reduction of the fatigue limitof the material.

Therefore, in the plunger pump cylinder as shown in FIG. 1, cracks startfrom the edges formed at the bore intersecting portions 14 within arelatively short period of time due to corrosive fatigue coupled withthe concentration of stress there. This tendency is greater the greaterthe corrosiveness of the fluid, and the higher the pressure. This canmake even an expensive plunger pump unusable.

DESCRIPTION OF THE PREFERRED EMBODIMENT Now, referring to FIG. 2 whichshows one embodiment of the present invention, on one side of cylinderbody 33 there is secured by any suitable means, such as bolts, a suctionport 31, and on the longitudinal axis of the cylinder body 33 at a rightangle to the axis of the suction port 31 there are arranged a deliveryport 32 provided in an outlet flange 41 and plunger 34 in opposedrelation to each other. Suction port 31, delivery port 32 and plunger 34are placed in communication with each other by a transverse hole 20 anda cylindrical bore 21 formed in the cylinder body 33.

Fitted within the cylindrical bore 21 of the cylinder body 33 is a valveseat body 22 which has a generally cylindrical form and a central roundlongitudinal bore 23. The diameter of bore 23 is enlarged at the upperportion of the valve seat so as to form a cylindrical delivery chamber43 in which delivery valve 39 is pressed against the valve seat formedat the upper end of central round longitudinal bore 23 by coil spring 40which is disposed between valve 39 and the bottom of the outlet flange41. The valve seat body 22 rests on suction valve support member 38,which is positioned within cylinder body 33 on the bottom of cylindricalbore 21 with a clearance between the peripheral surface of body 33 andbore 21. Valve seat body 22 is sealed in cylinder body 33 by a pair ofO-rings 24, one

near each end of valve seat body 22. The valve seat body 22 is held inplace by outlet flange 41 and stuffing box 35, which are aligned withcylinder body 33 and secured thereto by any suitable means such as boltsand sealed by packings 25 and 25'.

A suction chamber is formed between the bottom of valve seat body 22 andsuction valve support member 38 and is in fluid communication withsuction port 31 through transverse hole 20, an annular groove 26 in thewall of cylindrical bore 21 into while hole 20 which and several fluidpassages 27 which extend through valve seat body 22 from annular groove26 to the suction chamber 44. The exit ends of fluid passages 27 at thesuction chamber are normally closed by suction valve 36; which is urgedagainst the suction valve seat formed at the underside of valve seatbody 22 by coil spring 37 disposed between valve 36 and member 38.

Thus, according to the present invention, suction valve 36 and deliveryvalve 39 are positioned in cylinder 33 in such a way that during asuction stroke, the fluid is fed from inlet port 31 to longitudinal bore23 of valve seat body 22 through transverse hole 20, annular groove 26and fluid passages 27, while during a delivery stroke it is fed fromlongitudinal bore 23 to delivery port 32 through delivery valve 39.

It will be appreciated that in the present invention the plunger pumpcylinder is so constructed that at the portion 28 where the transversehole 20 intersects the annular groove 26 in cylinder body 33 onlysuction pressure is exerted, and this point is not affected by deliverypressure. Therefore, the cylinder body 33 of the plunger pump issubjected to only a definite low load due to the suction pressure atsaid intersecting portion 28 within cylinder body 33, and fatigue owingto the repeated load is not created at the intersection portion 28.

While there has been described and illustrated herein a preferredembodiment of the invention, it will be understood that modificationsmay be made without departing from the spirit of the invention. Forexample, the valve seat body can be divided into two or more parts, orthe stuffing box can be made integral with the cylinder body.

What is claimed is:

1. A plunger pump adapted for pumping corrosive fluids comprising acylinder body having a cylindrical ,bore with a first section of uniformdiameter and a second section of a smaller diameter than said uniformdiameter, said cylinder body further having an inlet port perpendicularto said first section; a valve seat body mounted within said firstsection of said cylindrical bore and having a longitudinal boretherethrough; a delivery flange attached to said cylinder body; a firstpacking disposed between said delivery flange and said valve seat body;a delivery valve urged against a seat on said valve seat body, astuffing box attached to said cylinder body; a second packing disposedbetween said stuffing box and said cylinder body; a plunger positionedwithin said stuffing box and adapted to move into said second section ofsaid cylindrical bore; a suction valve support member mounted withinsaid first section of said cylindrical bore of said cylinder body; asuction valve above said suction valve support member; means to urgesaid suction valve toward said valve seat b said suction valye havirygan openin therethrough less than the diameter 0 sald long1 udma bore ofsaid valve seat body; at least one fluid passage through said valve seatbody from said suction valve support member to said inlet port; and anannular groove around the inner periphery of said cylinder body andcommunicating between said inlet port and one end of said at least onefluid passage; said valve seat body and said suction valve supportmember being dimensioned to slidingly fit within said first section ofsaid cylindrical bore.

1. A plunger pump adapted for pumping corrosive fluids comprising acylinder body having a cylindrical bore with a first section of uniformdiameter and a second section of a smaller diameter than said uniformdiameter, said cylinder body further having an inlet port perpendicularto said first section; a valve seat body mounted within said firstsection of said cylindrical bore and having a longitudinal boretherethrough; a delivery flange attached to said cylinder body; a firstpacking disposed between said delivery flange and said valve seat body;a delivery valve urged against a seat on said valve seat body, astuffing box attached to said cylinder body; a second packing disposedbetween said stuffing box and said cylinder body; a plunger positionedwithin said stuffing box and adapted to move into said second section ofsaid cylindrical bore; a suction valve support member mounted withinsaid first section of said cylindrical bore of said cylinder body; asuction valve above said suction valve support member; means to urgesaid suction valve toward said valve seat body; said suction valvehaving an opening therethrough less than the diameter of saidlongitudinal bore of said valve seat body; at least one fluid passagethrough said valve seat body from said suction valve support member tosaid inlet port; and an annular groove around the inner periphery ofsaid cylinder body and communicating between said inlet port and one endof said at least one fluid passage; said valve seat body and saidsuction valve support member being dimensioned to slidingly fit withinsaid first section of said cylindrical bore.